Hydrophone suspension cable



United States Patent Charles V. Tallman Rye Beach, New Hampshire March 3, 1969 Nov. 17, 1970 By mwne assignments to the United States of America as represented by the Secretary of the Navy Inventor Appl. No. Filed Patented Assignee HYDROPHONE SUSPENSION CABLE 16 Claims, 7 Drawing Figs.

US. Cl 139/423,

139/385, 87/2 Int. Cl 003d 15/08 Field of Search 139/421,

[56] References Cited UNITED STATES PATENTS 1,697,660 l/1929 Rehfuss 139/385 3,199,548 8/1965 139/421 3,250,301 5/1966 139/422 3,315,559 4/1967 87/2 3,368,514 2/1968 Kelly, 114/235 Primary Examiner-Henry S. Jaudon Attorney-Edgar .I. Brower, Henry Hansen and B. Frederick Buchan, Jr.

ABSTRACT: Compliant, nonstrumming, interwoven composite cables for suspending hydrophones and other apparatus. Each cable includes a plurality of longitudinally extending, elastic warp elements bound together into a bundle by a single, multifilament, weft element interwoven to form noise suppressing fringes of weft element loops projecting transversely of the cable.

Patented Nov. 17, 1970 I 3,540,493

Sheet 1 of2 Fig 1 H 16 I5 14 n 14 n 14 f6 P m 1a INVENTOR. 29 CHARLES v. TALLMAN ATTORNEYS Patented Nov. 17, 1970 3,540,493

v INVENTOR.

32 as 35 31 CHARLES v. TALLMAN ATTORNEYS;

HYDROIIIONE SUSPENSION CABLE STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION This invention generally relates to interwoven composites and, more particularly, to elongated, compliant interwoven composites including longitudinally aligned warp elements of elastic material.

In order to most effectively support a hydrophone for sensing underwater signals, the support cable should be compliant in order to damp out the position changing effects of surface waves. Additionally, the hydrophone support cable should include some means such as fairings, thrums, or fringe for suppressing the noise attributable to transverse cable vibration stimulated by impinging fluid flows and should be capable of being rapidly paid out to facilitate rapid placement of the hydrophone. Heretofore, known compliant cables of the desired stretching capability have generally comprised a single strand of a solid elastomer. While pluralities of lilaments permanently attached to cable armor, extending from braided cable sheaths or inserted transversely of twisted cable configurations do exhibit noise suppressing properties, the known fringed cable configurations inherently would inhibit the normal compliance of the elastic cable. Additionally, present methods of manufacturing fringed cables can be relatively complex. time consuming or costly processes.

SUMMARY OF THE INVENTION It is the general purpose of this invention to provide an easily manufactured compliant support cable having noise suppressing fringes which do not interfere with or reduce the natural compliance of the cable Briefly, the general purpose of the invention may be accomplished by providing a cable including a plurality of longitudinally extending, elastic, warp elements interwoven into a coherent bundle by a continuous weft element in such a manner as to provide selvage loops extending from the cable and forming longitudinally arranged, noise suppressing fringes. More particularly, the invention contemplates an easily manufactured cable having a plurality of elastic warp elements interwoven by a single weft element in a particular configuration providing a cable having an increased range of stretch wherein the weft element does not inhibit stretching of the warp element. The invention additionally contemplates the provision ofa cable having a plurality of compliant longitudinal elements which, when stretched. form a fluid-pervious, cagelike, strum resistant structure further enhancing the reduction of noise attributable to impinginglluid flows. The invention further contemplates the provision of a cable of simplified construction having an odd number of warp elements of generally rectangular cross sec- IIOI'I.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 represents a longitudinal view ofa compliant fringed cable according to the invention in an untensioned condition;

FIG. 2 represents the cable of FIG. I in a tensioned condition; and I FIGS. 3, 4, 5, 6, and 7 represent enlarged exploded crosssectional views of five embodiments of cables according to the invention.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS Generally-referring to FIG. I, the interwoven composite cable 10 ofthe invention includes a number of longitudinally aligned elastic warp elements 11 which are bound together in a coherent bundle or body portion 12 of generally circular LII Ell

tion I2, which are set to optimize noise suppression while minimizing interference with cable pay out and with cable 7 elongation.

The warp elements I] are made from a compliant clastomer such as a high-stretch, highly resilient, synthetic rubber. The

warp material should have the desired degree of elasticity" enabling stretching within a desired range, such as six times its length in hydrophone applications, without exceeding its elastic limits and should possess sufficient tensile strength for the use envisaged. The elastomer from which the warp elements II are formed is preferably characterized by high stretch. high resilience, and low modulus. One suitable synthetic rubber is that used as a high-rebound golf ball winding. Generally, the number and cross-sectional area of the warp elements II are set to allow the warp elements 11 to function to support the desired load at near the minimum spring constant under the contemplated operating stress for the cable l0.

A suitable material for the weft element I4 is a high denier, multifilament filler yarn which is desirably nonabsorbent, possesscs a smooth textile hand, and has good elastic recovery. Polypropylene yarn is a suitable material for the weft element I4 because of its ability to retain its shape when either wet or dry, its lubricity, and its low specific gravity.

For example, a suitable compliant hydrophonc suspension cable according to the invention has been made from a weft element of.840 denier polypropylene multifilament yarnand l3 warp elements each of 20 gauge cut rubber such as Easthampton Rubber Thread Stock X I061 and each generally having a minimum tensile strength of 3500 p.s.i., an elongation of850 percent and a modulus of I75 p.s.i. at 500 percent.

One method of making the composite cable 10 ofthe invention is by weaving on a narrow-fabric loom. The elastic warp threads 11 are fed through the loom under controlled and uniform tension, while the weft yarn 14 used as fill is threaded by a shuttle through the warp elements II in such a pattern that the warp elements ll are gathered into the coherent bundle or body portion 12 by the weft element 14 under the tension applied by the shuttle. Lease wires are used in a regular pattern such as every fourth pass of the shuttle to form the loops l5 projecting from the coherent bundle or body portion I2. The pick count is set to give the desired degree of openness of the lattice or cap structure as is shown in the stretched cable 10 of FIG. 2. The tightness of the weave is adjusted to achieve a balance between the desired degree of cable stability and a minimal degree of constraint of the warp elements II by the weft element l4 occurring during longitudinal stretching of thccable. The weaving pattern or design is also selected so that the weft element l4 exerts minimal constraint on the warp elements ll during stretching.

Suitable weaving patterns are disclosed in FIGS. 3--7, inclusive. Referring to the enlargedQexploded pattern of FIG. 3 which includes seven warp elements, the weft element l4is interwovcn in alternate turns about the warp element bundle. generally designated 12, to form two loops I5 and 16 each extending outwardly of respective pairs of loop-retaining warp elements 21, 22, 23 and 24 arranged adjacent the center of the bundle l2. The weft element 14 is tucked under the warpelements 2| and 22 to form the left-hand loop 15 and passes outwardly of the peripheral warp element 25, inwardly of the peripheral warp .element 26, outwardly of the peripheral warp element 27, and inwardly of the warp element 23 to form the peripheral warp elements. passing inwardly of the peripheral warp elements 25 and 27 and outwardly of the intervening peripheral warp element 26. The next succeeding turn, not shown. forms the next adjacent pair ofloops. During the weaving process, restraining lease wires are used to form the loops 15 and 16; and the shuttle is used to apply tension to the weft element 14 and draw it in against the warp elements I] tending to bind them together in the coherent bundle or body portion 12 of FIG. 1. it can be noted from FIG. 3 that. considering each of the pairs of loop retaining elements 2l-22 and 23-24 as a unit or element. the weft element l4 passes inwardly of altcrnatc clcnicnts and outwardly of intervening elements on the alternate. loop-forming turns and passed outwardly of altermite elements and inwardly of intervening elements on the succeeding intervening turns. the inwardly passing weft clcments 14. in effect. being withdrawn from between the pairs of retaining elements 21-22 and 23-24 to form the loops 15 and 16. It should be noted that the term turn" as used herein refers to a complete encirclement of a particular group of warp elements and does not indicate the number of shuttle passes used in weaving one turn. For example, in FIG. 3. the loom may be set up so that the shuttle passes left around a lease wire (not shown) to form the lefthand loop 15. right around element 22, left around element 25, right around element 27, left around element 23, right around the other leasc wire (not shown) to form the right-hand loop 16. and then left to complete the loop-forming turn and begin the succeeding turn encircling the elements 21, 22, 26, 23 and 24.

The pattern generally indicated in the diagram of FIG. 4 having nine weft elements 11 is substantially like the seven element embodiment of FIG. 3 except that two additional peripheral warp elements 28 and 29 are interwoven into position adjacent the elements 21 and 24 and between the loops 15 and 16 on the side of the bundle 12 opposite the peripheral warp elements 25. 26 and 27. The loop-forming turn of the weft element 14 passes outwardly of the peripheral warp element 29 and inwardly ofthc loop-retaining element 21 to form the left-hand loop 15 and passes from the right-hand loop 16 inwardly of the loop-retaining element 24 and outwardly of the peripheral warp element 28 into the subsequent turn passing inwardly of the peripheral warp elements 28. 25 and 27 and encircling the loop-retaining elements 21. 22. 23 and 24 and the peripheral warp element 26 to draw the looprctaining elements into the generally centrally disposed position in the bundle or body portion 12.

The 11 warp element embodiment ofFlG. is similar to the 9 warp element of FIG. 4 except that two additional peripheral warp elements 31 and 32 are interposed between the peripheral warp elements 28 and 29. On the loop-forming turn the warp element 14 passes inwardly of the element 32. outwardly of the element 29. and inwardly of the element 21 to form the left-hand loop is interwoven with the elements 25. 26-and 27; and passes from the right-hand loop 16 inwardly of the retaining element 24. outwardly of the element 28. inwardly of the element 31. and outwardly of the element 32 through the succeeding turn encircling the loop-retaining elements 21, 22,23 and 24 and also the peripheral elements 26 and 31.

The embodiment of FIG. 6 includes 13 warp elements and has additional peripheral warp elements 33 and 34 interposed respectively-between the peripheral warp elements and 26 and the peripheral warp elements 26 and 27. The loop-forming turn of the weft element 14 encircles the peripheral warp elements 25, 26. 27. 28 and 29 passing inwardly of the peripheral warp elements 33. 34. 31 and 32 and the looprctaining elements 21, 22. 23 and 24. The subsequent turn cncircles the retaining elements 21. 22. 23 and 24 and the peripheral warp elements 32. 33. 34 and 31, passing inwardly of the periphery warp elements 29. 25, 26, 27 and 28.

The embodiment of FIG. 7 includes 15 warp elements and is similar to the embodiment of H0. 6, further including additional adjacent peripheral warp elements 35 and 36 interwoven into position between the peripheral warp elements 31 and 32. The loop-forming turn of the weft element 14 encircles the peripheral warp elements 36. 29. 25. 26. 27. 28 and 35. passing inwardly of the peripheral warp elements 32. 33. 34 and 31 and inwardly of the retaining elements 21. 22. 23 and 24. The subsequent turn encircles both the retaining elements 21. 22. 23 and 24 and the peripheral warp elements 32. 33. 34 and 31 passing inwardly of the peripheral warp elements 36. 29, 25, 26.27.28 and 35.

While it is contemplated that compliant. strum-resistant cables 10 according to the invention may have more than l5 warp elements. the rctractivc force of the compliantcahlell) can be adjusted more efficiently by increasing the cross-sectional area of the individual warp elements. Additionally. although no specific examples are shown. it is contemplated that cable configurations according to the invention can in clude even numbers ofwarp elements.

Referring to FIG. 2. when the cable 10 is longitudinally stretched. adjacent turns of the weft element 14 become further spaced apart forming generally a cagclikc construction with the warp elements 11 wherein moving water is free to pass between the slightly spaced warp elements 11. This particular cable configuration greatly inhibits the tendency of the cable 10 to strum in response to transverse fluid flows. The weft element 14 does not tend to constrict the warp elements 11 during stretching becausc the loops l5 and 16 enable the encircling weft element 14 to loosen slightly, the warp clements 11 being free to assume their normal cross-sectional configuration in those areas engaged by the weft element 14. When the tension applied to the cable 10 is removed, the warp elements 11 expand slightly in cross-sectional area and reassume the configuration of FIG. 1 wherein a substantially contiguous. touching relationship exists between adjacent warp elements 11. The unstressed cable 10 may be easily and compactly stored for rapid pay out. The loops 15 and 16 function in a fluid flow environment to damp out or suppress noise at-' tributablc to cable strum and yet offer less resistance to cable pay out than do cables having larger fairing elements.

Obviously manymodifications and variations of the present invention are possible in view of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

lclaim:

1. A compliant cable comprising:

a plurality of longitudinally extending warp elements made ofclastic material; and

a continuous weft element interweaving with said warp elements to form a body portion and intermittently projecting transversely ofsaid body portion as loops to form longitudinally aligned fringes on opposite sides of said body portion for inhibiting cable strumming.

2. A cable according to claim 1 further comprising said weft element being interwoven with said warp elements in a pattern permitting lateral separation of said warp elements and longitudinal separation of longitudinally adjacent portions of said weft element to form a fluid pervious cage structure when said cable is longitudinally tensioncd.

3. A cable according to claim 2 further comprising said loops including sufficient lengths of said weft element to permit warp clement elongation in a range including six times their untcnsioned length.

4. A cable according to claim I further comprising:

some of said warp elements being loop-retaining elements;

and

said weft element being interwoven in a series of turns. al-

ternatc turns being loop-forming turns wherein said loops of said weft clement extend from between adjacent loopretaining warp elements and intervening turns encircling said loop-retaining warp elements.

,5. A cable according to claim 4 further comprising:

said warp elements further including peripheral warp elements; and

said turns of said weft element encircling said loop-retaining elements further encircling at least one ol said peripheral warpelements.

6. A cable according to claim 5 further comprising said loop-retaining warp elements being arranged adjacent the center of said body portion.

7. A cable according to claim l further comprising:

said warp elements including a plurality of pairs of loopretaining warp elements and a plurality of peripheral warp elements; and

said weft element being interwoven alternately about said pairs of loop-retaining warp elements and said peripheral warp elements in a succession of turns wherein said weft element passes inwardly of each said pair of loop-retaining elements on alternate turns and encircles said pair of loop-retaining warp elements on intervening turns, said alternate turns including said loops extending from between adjacent loop-retaining elements in said pairs.

8. A cable according to claim 7 further comprising at least one of said loop-retaining elements of each of said pairs being arranged centrally ofsaid body portion.

9. A cable according to claim 8 further comprising:

LII

said weltelement being a multiiilameut polyethylene yarn;

and said warp elements being made of an elastomeric material able to undergo elongation in a range including six times its untensioned length. l0. A cable'according to claim 9 further comprising said warp elements having rectangular cross-sectional configurations.

ILA cable according to claim 8 further comprising: an odd number ofwarp elements; and a single weft element. 12. A cable-according to claim ll further comprising 7 warp elements.

13. A cable according to claim ll further comprising 9 warp elements.

[4. A cable according to claim It further comprising ll warp elements.

15. A cable according to claim ll further comprising l3 warp elements.

16. A cable according to claim ll further comprising [5 warp elements. 

